Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-Complexes
The aim of the research is the development of a one-pot method for the synthesis of lignans, natural compounds that show a wide spectrum of biological activities. For this purpose, the <i>ansa</i>-zirconocenes of various structures were tested as catalysts of allylbenzene cyclometalation...
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2021-11-01
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author | Pavel V. Kovyazin Pavel V. Ivchenko Ilya E. Nifant’ev Lyudmila V. Parfenova |
author_facet | Pavel V. Kovyazin Pavel V. Ivchenko Ilya E. Nifant’ev Lyudmila V. Parfenova |
author_sort | Pavel V. Kovyazin |
collection | DOAJ |
description | The aim of the research is the development of a one-pot method for the synthesis of lignans, natural compounds that show a wide spectrum of biological activities. For this purpose, the <i>ansa</i>-zirconocenes of various structures were tested as catalysts of allylbenzene cyclometalation with ethylaluminum dichloride (EtAlCl<sub>2</sub>) and Mg. The effects of the organophosphorus compounds, hexamethylphosphoramide (HMPA) and triphenylphosphine (PPh<sub>3</sub>), on the chemo- and regioselectivity of the reaction were studied. The use of <i>η</i><sup>5</sup>-indenyl or fluorenyl <i>ansa</i>-complexes with ethanediyl or dimethylsilylene bridges, as well as a biscyclopentadienyl complex with Si-bound ligands as catalysts in the presence of HMPA, yields the formation of cyclometalation products in a total yield of 70%. Cyclometalation product composition is represented by two regioisomers, 3,4-dibenzyl- and 2,4-dibenzyl-substituted alumolanes, with a ratio of (1-2):1, in which hydrolysis provides corresponding dibenzylbutane lignan and 9,8′-neo-lignan. |
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issn | 2673-4583 |
language | English |
last_indexed | 2024-03-11T06:46:13Z |
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spelling | doaj.art-efdeb8393fef4fabaf3ebe142cc4f8422023-11-17T10:18:52ZengMDPI AGChemistry Proceedings2673-45832021-11-01816010.3390/ecsoc-25-11776Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-ComplexesPavel V. Kovyazin0Pavel V. Ivchenko1Ilya E. Nifant’ev2Lyudmila V. Parfenova3Institute of Petrochemistry and Catalysis of Russian Academy of Sciences, Prospekt Oktyabrya, 141, 450075 Ufa, RussiaA. V. Topchiev Institute of Petrochemical Synthesis RAS, Leninsky Avenue 29, 119991 Moscow, RussiaA. V. Topchiev Institute of Petrochemical Synthesis RAS, Leninsky Avenue 29, 119991 Moscow, RussiaInstitute of Petrochemistry and Catalysis of Russian Academy of Sciences, Prospekt Oktyabrya, 141, 450075 Ufa, RussiaThe aim of the research is the development of a one-pot method for the synthesis of lignans, natural compounds that show a wide spectrum of biological activities. For this purpose, the <i>ansa</i>-zirconocenes of various structures were tested as catalysts of allylbenzene cyclometalation with ethylaluminum dichloride (EtAlCl<sub>2</sub>) and Mg. The effects of the organophosphorus compounds, hexamethylphosphoramide (HMPA) and triphenylphosphine (PPh<sub>3</sub>), on the chemo- and regioselectivity of the reaction were studied. The use of <i>η</i><sup>5</sup>-indenyl or fluorenyl <i>ansa</i>-complexes with ethanediyl or dimethylsilylene bridges, as well as a biscyclopentadienyl complex with Si-bound ligands as catalysts in the presence of HMPA, yields the formation of cyclometalation products in a total yield of 70%. Cyclometalation product composition is represented by two regioisomers, 3,4-dibenzyl- and 2,4-dibenzyl-substituted alumolanes, with a ratio of (1-2):1, in which hydrolysis provides corresponding dibenzylbutane lignan and 9,8′-neo-lignan.https://www.mdpi.com/2673-4583/8/1/60cyclometalationalkeneszirconoceneslignane |
spellingShingle | Pavel V. Kovyazin Pavel V. Ivchenko Ilya E. Nifant’ev Lyudmila V. Parfenova Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-Complexes Chemistry Proceedings cyclometalation alkenes zirconocenes lignane |
title | Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-Complexes |
title_full | Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-Complexes |
title_fullStr | Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-Complexes |
title_full_unstemmed | Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-Complexes |
title_short | Synthesis of Dibenzylbutane and 9,8′-Neo-Lignans via Cyclometalation of Allylbenzene by EtAlCl<sub>2</sub> and Mg in the Presence of Zr <i>ansa</i>-Complexes |
title_sort | synthesis of dibenzylbutane and 9 8 neo lignans via cyclometalation of allylbenzene by etalcl sub 2 sub and mg in the presence of zr i ansa i complexes |
topic | cyclometalation alkenes zirconocenes lignane |
url | https://www.mdpi.com/2673-4583/8/1/60 |
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